Pressure-membrane extraction apparatus



July 13, 1944.

L. A. RICHARDS PRESSURE-MEMBRANE EXTRACTION APPARATUS Filed July is,1941 '28 INVENTOR LORENZO AFRICHARDS I ATTORNEYS Patented July 18, 1944PRESSURE-MEDIBRANE EXTRACTION APPARATUS Lorenzo A. Richards, Riverside,Calif.; dedicated to the free use of the People in the territory of theUnited States Application July 16, 1941, Serial No. 402,715 6 Claims.(o1.21o-1s5) renamed under the act of March 3, 1883, as amended April30, 1928; 370 0. G. 757) This application is made under the act of March3, 1833, as amended by the act of April. 30, 1928, and the inventionherein described and claimed, if patented, may be manufactured and usedby or for the Government of the United States of America forgovernmental purposes without the payment to me of any royalty thereon.

I hereby dedicate the invention herein described to the free use of thepeople in the territory of the United States to take effect on thegrantingof a patent to me.

This invention relates to liquid extraction and one of the objects isthe provision of an apparatus for use in extracting liquidsrfrommaterials which are porous, permeable or granular, such as soil.

In general, this invention comprises a pressure chamber having amembrane wall which, when. wetted with a mixture of a liquid to beextracted and a gas used to maintain pressure in the pressure chamber,is permeable to the liquid, but impermeable to the gas.

In the accompanying drawing there is illustrated an embodiment of thisinvention in one of its preferred forms, in which drawing:

Figure 1 is a plan view of the embodiment; an Figure 2 is a sectionalong the line 2-2 of Figure 1.

Referring with more particularity to the drawing, in which like numeralsdesignate like parts,

the embodiment illustrated comprises a chamber composed of a cylinder ontop of which is removably disposed a cover plate 6. Beneath said coverplate there is disposed a flexible diaphragm l of soft rubber or othersuitable material. An

annular gasket 8 of rubber, or other suitable material, is disposedbetween the diaphragm 7 and the top rim of the cylinder 5. In order toprovide a more effective seal, the top rim of the cylinder 5 is providedwith a groove 9.

Against the bottom rim of the cylinder 5 there is disposed anothergasket It, like the gasket 8, the rim of the cylinder at this pointhaving also a groove H to provide a better seal between the gasket andthe cylinder. Against the bottom of the gasket It], a membrane ll ofCellophane, or other suitable material, is placed and against the bottomof the membrane l2 is a screen I 3, preferably brass and of 120 mesh.The screen I3 is attached to the brass plate by the annular rim of metalI4 which may be solder or tin or other suitable material. This rim isdirectly below the gasket Ill. The screen I3 is supported by the plate[5 which may be of any suitable material, such as brass. The plate l5rests on a bottom cover plate l6 which is connected by bolts ll carryinnuts l8 to the top cover plate 6, whereby the entire assembly is heldtogether.

Lugs 19, 2! and 2! project from the cylinder 5 and engage the threads ofbolts 22, 23 and 24 disposed through the bottom cover plate 16. By thesemeans, the assembly against the bottom rim of the cylinder 5 can be heldin place while the top cover plate and diaphragm 1 are removed tocharge'the chamber with the material from which the liquid is to beextracted.

An outlet tube 25 is disposed through the bottom cover plate It andthrough the plate l5, the upper end of said tube being flush with thetop of the plate l5.

Through the wall of the cylinder 5, near the upper rim thereof, a tube26 is tapped and is adapted to be connected to a source of gas underpressure. Through the top cover plate 6 another tube 21 is tapped whichis also adapted to be connected to a source of gas under pressure.

Suitable leg supports 28 are provided on the bottom cover plate l6,

To use the device, the nuts l8 are removed from the bolts I! and the topcover plate 6, together with the diaphragm l, is removed. The materialto be treated is then placed in the chamber and the diaphragm I with thetop cover plate 6 is replaced, after which the nuts l8 are tightened onthe bolts ll.

Pressure inside of the chamber is then increased by introducing gasunder pressure through the tube 26. Liquid from the material beingtreated touches the membrane l2 and passes through the pores thereofinto the interstices of the screen l3 where it is drained through theoutlet tube 25. As the material in the chamber becomes dehydrated, acontinuous gas phase is established throughout the mass of material.When this continuous gas phase is established, the liquid in the poresof the membrane forms a meniscus with the gas and said meniscus preventsthe flow of gas through these pores, the while permitting liquid fromthe material being treated to flow into the liquid phase of themeniscus. The meniscus will be maintained so long as liquid from thematerial being treated flows in to the water phase of the meniscus andso long as this meniscus is maintained, the flow of gas through thepores of the membrane will be prevented.

By maintaining the pressure in the chamber, there is established in thegas-liquid interface at the upper surface of the membrane an equivalentcurvature determined by the pressure difierential between the two sidesof the membrane. The substantially free movement of water through themembrane maintains this same curvature in the liquid interface at thecontact points between the membrane and the material. Thus there isestablished a curvature gradient across the layer of material in contactwith the membrane. The pressure gradient corresponding to this curvaturegradient moves the liquid through the unsaturated material toward themembrane. When equilibrium is through loss of liquid, the interfacecurvature of the liquid throughout the material will be the same as atthe membrane and passage of liquid through the membrane will cease.

As the liquid is extracted from the material and passes out of thechamber, the material will have a tendency to shrink out of contact withthe membrane. In order to maintain a constant U pressure of the materialagainst the membrane,

gas under pressure in excess of thepressure in the chamber is introducedthrough the tube 21 against the diaphragm I, which thereby is distendedinto contact with the material and forces it against the membrane.

Having thus described my invention, I claim:

1. A device of the character described comprisin a chamber, a porousmembrane forming .one wall of said chamber, means for introducing gasunder pressure into said chamber, and means for urging material in saidchamber against said membrane when gas under pressure is in saidchamber.

2. In a device of the character described having a chamber, one wall ofwhich is-a porous membrane, a screen against the outer side of saidmembrane. a plate against said screen, a drain pipe through said plateto carry off liquid between said plate and membrane, and means for introducing gas, under pressure into said chamber.

3. A device of the character described comprisreached ing a chamberhaving a removable cover plate on one side and a porous membrane on theother, a flexible diaphragm between said cover plate and the sides ofthe chamber, and means for introducing gas under pressure between saiddiaphragm and said cover plate so as to urge material in said chamberagainst said membrane.

4. The method of extracting liquid from an unsaturated porous solidmaterial, comprising placing the material in contact with one face of aporous membrane and establishing and maintaining by gas pressure acontinuous gas phase throughout said material and liquid-gas interfacesacross the pores of the membrane.

5.An apparatus comprising a cylindrical shell, a rigid top cover memberand a rigid bottom cover member on said shell, a flexible gas-tightdiaphragm on said shell beneath said top cover 'member, a porousmembrane below said shell over said bottom cover member, a foraminoussheet below said porous membrane to hold it offset from the bottom covermember, a drain pipe through said bottom cover member communicating withthe interstices of said foraminous mem-. her, a tube through said shellcommunicating with the space between said diaphragm and said membrane,and a tube through the top cover member communicating with the uppersurface of the diaphragm.

6. A device of the character described comprising a chamber having aremovable cover plate on one side and a porous membrane on the other, aflexible diaphragm between said cover plate and the sides of thechamber, and means for introducing gas under pressure between saiddiaphragm and said cover plate so as to urge material in said chamberagainst said membrane, and means for introducing gas in said chamberbetween said diaphragm and said'membrane.

LORENZO A. RICHARDS.

